Apparatus for treating the surface of prismatic bodies



Jan. 20, 1970 GQCHAUVIN ETAL 3,4915013 APPARATUS FOR TREATING THE SURFACE OF PRISM-ATIC BODIES Filed Aug. 16, 1966' 5 Sheets-Sheet 1 FIG] Jan. 20, 1970 5, c uvm ET AL 3,491,013

PPARATUS FOR TREATING THE SURFACE OF fRISMATIC BODIES Filed Aug. 16, 1966 3 Sheets-Sheet 2 Jan. 20, 1970 G. CHAUVIN ETAL APPARATUS FOR TREATING THE SURFACE OF PRISMATIC BODIES Filed Aug. 16. 1966 3 Sh ets-Sheet 5 FIG?) rm. (:1. (E2311 /78 U.S. Cl. 204-413 s Claims.

5 ABSTRACT OF ,THE IIISCLOSURE Surface treatment of prismatic parts is obtained by mounting the parts in coil springs to which an electric potential is applied. The springsare rotated in an electrolytic bath and the parts periodically flip-over in the springs during rotation thereof.

The present invention is directed to a method whereby electrically conductive parts are subjected to an electrolytic or chemical surface treatment which is at least superficial and is further concerned with a device for the practical application of said method; both said method and said device are of interest for the complete treatment (degreasing, pickling, washing and metal coating) of uranium parts "or parts formed of a uranium base alloy.

The principle of electrolytic surface treatment of electrically conductive parts is well known: the parts to be treated are immersed in a bath of suitable composition and constitute one of the electrodes of an electric circuit which is closed by electrodes placed in the bath. By sending an electric.v current through the bath, a number of different treatments can be carried out such as pickling, coating with metal and so forth.

French Patent No. 1,260,086 as granted to Commissariat a lEnergie Atomique describes a method for the electrolytic surface treatment of parts of revolution. This method consists in supporting the parts to be treated 3,491,013 Patented Jan. 20, 1970 axis or about a line parallel thereto so as to produce the complete reversal of said part and the modification of its within a helical spring which is disposed horizontally in the bath and through which electric current is supplied to the part, and. in causing said spring to rotate during the operation so as to modifythe zonesof contact between the spring and the part to-be treated while ensuring uniformity of treatment over the entire. surface of the part.

Unfortunately, this solution. is not always applicable to the treatmentof parts which are not of revolution. In particular, in thecase ofsparts having a cross-section of polygonal configuration, the part which is placed inside the helical spring slides along the coils of the spring instead of. rotating, which consequently destroys the advantage of the solution proposed by the French patent.

The present inventionis directed to the basic concept of a method which canbe appliedto parts having a crosssectional configuration whichis not circular and e's ii ecially to parts of polygonal cross-section.- With this object in mind, the invention proposes a method of chemical and/ or electrolytic surface treatment of. prismatic parts each having in cross-section n'long sides of substantially equal length, said method consisting in supporting the part to be treated on the lower portion of a coiled spring having a horizontal axis, the coils'o'f which are placed around a prism, the transverse cross-section of which has the shape zones of contact with the spring.

The expression long sides which has been employed above is intended to refer to those sides on which the part can be supported. In the majority of cases (especially in the case of parts having a cross-section in the shape of a regular polygon), all of the sides must be considered as long sides. In other instances, and especially in the case in which the part is constituted by a plate having small thickness compared to its width, only two sides of the cross-section out of four must be considered as long sides.

In order to prevent any lack of uniformity in the surface treatment, it is necessary to ensure that the number N is incommensurate with the number n, thereby preventing any periodicity of contact between the same zones of the part. The easiest method of satisfying this condition is of course to give N a value which is equal to n+1 although this expedient would only be applicable if the spring were endowed with a continuous movement of rotation which would bring the plate successively against the N sides. On the other hand, if the movement of rotation were reciprocal or, in other words, if the spring were endowed with an alternating motion, the number of contact sides would in that case have to be greater than n. However, this solution is much less satisfactory than the continuous movement of rotation of the spring by reason of the periodicity which it entails.

A very wide choice of different methods is available for the purpose of driving the spring in rotation; it is possible in particular to make use of a prismatic rod to which the spring is fastened, the said rod having a Width of the same order as the length of the side of the polygon. The movement of rotation of said rod initiates the rotation of the spring.

The disadvantage of this solution, however, lies in the fact that it cannot readily be carried into practice when the transverse cross-section of the part to be treated has a small number of long sides n (n=2 or 3). In this instance also, there is a danger that the part will slide instead of rotating, especially by virtue of the fact that the overall size of the rod in addition to that of the part itself makes it necessary to employ a spring having a large diameter and a large number of sides.

One expedient which proves much more satisfactory, especially when the parts to be treated have relatively small dimensions and/or a small number of sides, consists in mounting a plurality of springs in parallel relation on a rotating system which is adapted to rotate about an axis parallel to that of the springs: the rotation of the springs about their axes is then accompanied by a movement of translation along a circle, but this combination of movements does not present any disadvantage.

This invention also has for its object a device for the practical application of the method aforesaid. The device in accordance with the invention comprises, within an elecof a regular polygon having N sideswhich are of slightly I trolytic treatment tank which contains a bath, at least one spring having a horizontal axis, the coils of which are placed around a prism having a transverse cross-section in the shape of a regular polygon with N sides and the lower portion of said spring which contains the part being immersed in said bath, means for driving said spring in rotation about its axis and means for supplying said spring with electric current.

The invention also has for its object by way of novel industrial products the prismatic parts of polygonal transverse cross-sectional configuration which are treated in accordance with the method hereinabove defined.

The invention also consists in other arrangements which are preferably employed in conjunction with the preceding out which can also be employed independently thereof. All of these arrangements will become more readily apparent by perusal of the following description of one mode Jf application of the invention which is given by way of non-limitative example, reference being had to the accompanying'drawings, in which: 1

'FIG'. 1 is a view in elevation of a nickel-plating appara- ;us in accordance with the invention, as shown in crosssection along adiametral vertical plane;

FIG. 2 'is a viewin the direction of the arrow F of FIG. 1 whichshows diagrammatically one of the flanges of the :lrum and the successive positions which are taken up by the parts to be treated as the drum rotates, said parts being constituted by strips having a flat rectangular crosssection;

FIG. 3 is a view in perspective of the complete drum;

FIG. 4 is a diagrammatic detail view showing one of :he springs of the drum of FIG. 3;

FIG. 5 is an end view of the spring of FIG. 4 and of the strip which is placed therein;

FIG. 6 which is similar to FIG. 5 shows a spring for the treatment of parts having a square cross-sectional configuration.

The device A in accordance with the invention is disposed during operation in an electrolytic bath 10 contained in a tank, only the bottom 11 of which is shown in FIG. 1. Electrodes which are not shown in the drawings are immersed in the bath 10 which is constituted by a solution of a nickel salt when the operation to be performed on the parts to be treated is a nickel-plating process.

The device A comprises a support frame constituted by two parallel side-plates 12 and 14 which are placed on the bottom 11 of the tank, the side-plate 14 being adapted to carry a motor 16 for driving the device. The moving portion of the device A is constituted by a drum 18 which is rotatable about a horizontal shaft composed of two Flanges 20 and 22 carried by a shaft 24 which is carried by roller-bearings 25 mounted in the side-plates 12 and 14. Said roller-bearings are of plastic or metallic material which affords resistance to the corrosive action of the solutions contained in the tank. The flanges 20 and 22 are maintained assembled together by means of a central spacer tube 26 and by means of nuts 28 and 30 which are screwed on threaded portions of the shaft 24, provision being additionally made if necessary for lateral spacer -nembers 31.

There are formed at equal angular intervals in the flange Z recesses 32 which are located in oppositely-facing relation to openings 34 of corresponding shape which are pierced in the flange 22. The recesses 32 are designed to accommodate springs 36 which are inserted through the openings 34 and secured in position by means of a retaining plate 39 which is fixed to the flange 22 by means of screws 40 which engage in the ovalized holes 41 of the plate so as to permit a slight angular displacement of this latter with respect to the flange. Said angular displacement is intended to permit the insertion of the parts to be treated in the springs and to maintain said parts within said springs during treatment as will be explained below.

The springs 36 which are shown and which are intended for the treatment of strips 38 which have a transverse cross-section of flattened rectangular configuration (as shown in FIGS. 2 and are made up of three straight wires such as the wire 43 (as shown in FIGS. 4 and 5) which delimit the angles of a virtual parallelipiped having a cross-section in the shape of an equilateral triangle and around which are wound the coils of the spring proper.

In order to prevent the direct passage of electric cur.

rent between the spring 36 and the bath, or rather in order :0 limit the current transmission zone to that portion of the surface of the coils which comes into contact with the strip to be treated, the wire which constitutes the spring 36 is provided with an insulating covering except on the internal face of the coils. The simplest solution consists in forming the spring of wire which is insulated by a covering of polyvinyl chloride, for example, and in removing this covering within the coils after the spring has been formed. a v

Electric current can be supplied to the springs in a number of different ways. In the embodiment which is illustrated, the terminal portion of thewire which constitutes the coils of the spring traverses the flange 20 and is clamped between saidflange 20 and a nickel ring 42,

which is secured to the flange by means of screws 44. The ring 42 is supplied with current by means of a conductor 46 terminating in a friction-contact brush or collector brush 48 which is applied against the ring, as shown in FIG. 1. The other components of the drum and of the frame must of course be insulated. For this purpose, an acrylic polyester can be employed such as methyl methacrylate so as to form the flange 22 and the retaining plate 39, and another plastic such as polyvinyl chloride can be employed so as to form the shaft 24, the spacer members 26 and 31, the flange '20 and the nuts 28 and 30. That portion of the current supply ring 42 which is not in contact with the collector-brush 48 as well as the screws 44 and the metal nuts 49 which serve to secure the spacer members 31 can all be advantageously provided with an insulating covering. This precaution makes it possible to prevent leakage currents as well as excessive deposition of nickel on the ring 42.

The drum 18 is driven in rotation from the motor 16 by any suitable means such as a driving belt 50 which is passed over pulleys respectively driven by the motor and fixed to the shaft 24.

The device herein described is intended for the treatment of parts which have a cross-section of flat rectangular configuration, that is to say having two long sides: the coils of the spring are accordingly disposed along a para]- lelipiped having a triangular cross-section, although other shapes can be envisaged such as a pentagonal crosssection. However, the device is suitable not only for parts of flat rectangular shape but can very easily be adapted to parts'having other shapes; by way of example, FIG. 6 shows a spring 36' having a cross-section in the shape of a regular pentagon for the purpose of treating parts such as the part 38' of square cross-sectional configuration.

The operation of the device will now be described in reference to FIGS. 1, 2 and 3. When the device has been withdrawn from the nickel-plating bath and the current supply is switched off, 'the drum 18 is loaded with parts to be treated and which consist of strips 38. In order to carry out this operation, the screws 40 are slackened off and the retaining plate 39 is moved into the end angular position thereof in which the elongated slots or passageways 52 which are provided in said plate (as shown in FIGS. 1 and 3) coincide with the openings 34. The strips 38 are then inserted through these openings, whereupon the plate 39 is brought back into its locking orientation (as shown in chain-dotted lines in FIG. 2) and locked in position by means of screws 40. Recessed portions56 of suitable shape (as shown in FIGS. 2 and 3) which are formed in the plate 39' can also permit the insertion of nuts 49 for securing the spacer members 31.

Once the drum has been loaded, the device is introduced successively in each of the degreasing, pickling and washing baths, then in the electrolytic coating bath (as shown in FIG. 1). The drum is set in rotation by means of the motor 16 and an electric supply voltage is applied between the springs. 36 and electrodes which are placed in the bath, the springs being connected to the negative pole. During the rotation of the drum in the direction shown by the arrow 1 in FIG. 2, the strips 38 are subjected to a periodic flip-over motion (arrow j) which ensures uniform nickel-plating over their entire surface. It is apparent in particular that each strip 38 has an orientation which is opposite to its initial orientation after one full revolution of the drum, any lack of uni formity being consequently avoided.

By Way of example, it can be noted that a device which is constructed for the purpose of nickel-plating uranium strips measuring 15 mm. x 3 mm. in transverse crosssection and approximately 60 mm. in length comprises a drum 180 mm. in diameter which carries twelve springs of substantially triangular cross-section and formed of nickel wines 1 mm. in diameter. The small plates which are introduced within the springs are subjected to a treatment involving suitable surface preparation and washing followed by a nickel-plating process during which the drum rotates at a speed of rpm.

The device which has just been described and the process which entails the utilization of said device are in no may limited to the metallic coating of parts and are applicable to any operation involving bath treatment; the term bath treatment is used here in a wide sense and includes within its scope such treatments as pickling, degreasing, washing, passivation and so forth which can either precede or follow the electrolytic coating process.

It 'will be readily understood that the invention is not limited in any sense to the single embodiment which has been illustrated and described and it must be understood that the scope of this patent extends to all alternative forms or all or a part of the arrangements described which remain within the definition of equivalent means.

What we claim is:

1. An apparatus for the surface treatment of prismatic parts, each having in transverse cross-section n long sides of substantially equal lengths, said apparatus comprising a tank containing an electrolyte, a rotatable support mounted horizontally in said tank, means to rotate said support so that at least part of said support is immersed in said electrolyte, means for supporting said prismatic parts in said support for causing periodic flipover of the prismatic parts during rotation of said support, said means comprising at least one electrically conductive coil positioned sufliciently near the periphery of said support so that the coil becomes immersed, said coil defining a cylinder axially parallel to the axis of said support and having a transverse cross-section in the shape of a regular polygon With N sides which are of slightly greater length than said long sides of each part, the number N being greater than n, and means to eflect an electrical potential on said coil to cause treatment of said parts.

2. A device as described in claim 1 wherein said support is a drum, a plurality of springs fixed at uniform regular intervals about the axes of said drum, said driving means rotating said drum.

3. A device as described in claim 2, said drum being partially immersed in the electrolytic bath, said means for supplying electric current comprising an electrically conductive ring integral with the peripheral portion of said drum and connected to each of said springs and a collector brush outside the bath and in sliding electrical contact with said ring.

4. A device as described in claim 2, said drum comprising two flanges of insulating material held together by spacer members, one of said flanges carrying said ring and having recesses for receiving the terminal portions of said springs, the other of said flanges having slots through which said springs are inserted and located opposite to said recesses and a plate for retaining said springs fixed to said second flange.

5. A device as described in claim 4, said retaining plate being fixed to the corresponding one of said flanges by connecting means providing an angular displacement of said plate between a first position for insertion of parts to be treated in said springs through said slots and a second position holding the parts in said springs.

References Cited UNITED STATES PATENTS 3,038,851 6/1962 Jackson 204213 ROBERT K. MIHALEK, Primary Examiner US. Cl. X.R. 204740 

